Levels of interleukin-18 are markedly increased in Helicobacter pylori-infected gastric mucosa among patients with specific IL18 genotypes

Abstract

Background. The cellular immune response in gastric mucosa infected with Helicobacter pylori is proposed to be predominantly of the T helper cell type 1 type. Methods. Interleukin (IL)-18, IL-12, and interferon (IFN)-γ levels were measured in gastric mucosal biopsy specimens by reverse-transcription polymerase chain reaction (PCR) and by enzyme-linked immunosorbent assay; IL18 polymorphisms were determined by PCR. Results. Biopsy specimens from 128 patients (56 with nonulcer dyspepsia, 28 with gastric ulcers, 28 with duodenal ulcers, and 16 with gastric cancer) were examined; 96 patients had H. pylori infection. IL-18 levels were markedly up-regulated in mucosa infected with H. pylori (P < .001), whereas IL-12 and IFN-γ levels were independent of H. pylori status. IL-18 levels correlated with IFN-γ levels only in infected patients (R = 0.31 to R = 0.51). IL-18 levels were the determining factor for monocyte infiltration in H. pylori-infected mucosa (P